1. Field of Art
This invention relates to structural members and assemblies thereof, used in various fabrication purposes. With more particularity, this invention relates to structural members preferably (but not exclusively) formed from plastic or composite materials, and a support mat assembly fabricated therefrom.
2. Related Art
Structural members of many different varieties are old in the art. In particular, so-called “I-beams,” bearing that name because the cross-sectional shape of the structural member resembles the letter “I,” have been used for many, many years in building fabrication and the like. Such I-beams were primarily made of iron or steel. The typical I-beam, well known in the art, has two spaced-apart parallel flanges connected by a central web. A key advantage to use of an I-beam, as opposed to a solid beam having the same outer dimensions, is that the I-beam is much more structurally “efficient.” By that is meant that a tremendously reduced volume and weight of material is needed to yield a structural member having nearly the same rigidity as a solid beam. This is because the greatest rigidity is contributed by material at the most distant points from the bending axis of the beam. In a solid beam, the large volume of material relatively close to the bending axis contributes relatively little to rigidity.
In addition, due to their geometry, I-beams have high vertical or compressive load capacity (that is, loads perpendicular to the face of the flange). Thereby, I-beam structural members are suitable and desirable for support surfaces.
A drawback to I-beams is relatively low torsional (twisting) rigidity. This results, in part, from the absence of the material adjacent the central web.
These properties of I-beam structural members make them suitable for building transit and support areas for heavy equipment, especially on relatively soft terrain. Such transit and support areas are frequently needed in, for example, construction, military, and oilfield applications. However, it is not feasible to use iron or steel I-beams for such applications, as they would be far too heavy and too expensive, and further are subject to corrosion. While it may be possible to form I-beams out of lighter and less expensive materials such as wood, decay is a problem, since the application is often in a wet, soft terrain environment. Wooden members therefore often turn out to be single-use members due to rotting, breaking and splintering from high loads, etc.
It is desirable to form mat assemblies suitable for use in soft terrain, which combine the favorable attributes of relatively low cost, low weight, high load bearing capacity, and resistance to decay. The present invention combines certain favorable aspects of I-beams (high rigidity, high load bearing capability), while maintaining vertical load capacity and increasing torsional rigidity through the addition of filler blocks, and with highly decay-resistant materials (plastic or composite materials, or light weight metals such as aluminum), to form very strong mat assemblies having a reasonable cost.